The invention relates both to a release device for an inflatable element for protecting a vehicle against impact, which element, once inflated, presents a general shape that fits closely over the region of the vehicle to be protected, and to a protection device for protecting a vehicle against impact, the protection device including an inflatable element provided with such a release device. The release device of the invention preferably applies to devices for providing impact protection in the rail industry, for which the inflatable protection element is particularly bulky.
Inflatable protective cushions disposed at the front of rail vehicles, such as disclosed in publication FR 2 764 855 in the name of the Applicant, to absorb shock during impact with an obstacle, present the characteristic of being large in volume and thus requiring a very large quantity of gas to be injected under high pressure to ensure that the inflatable cushion is deployed rapidly. The inflatable cushions are provided with release orifices enabling the gas to be released progressively during impact so as to absorb the energy of the impact. Unfortunately, however, such orifices present the drawback of allowing some of the gas to escape during the stage of filling the inflatable cushion, thus contributing to further increasing the quantity of gas required to deploy the inflatable cushion.
It is known, in particular in the automobile industry, to remedy that drawback by disposing a membrane over the release orifices of the inflatable cushion so as to close said orifices during the stage of inflating the protective cushion, the membrane being designed to tear under excess pressure due to impact in order to enable the gas to be freed and the shock to be absorbed. Such a solution is disclosed in publication FR 1 571 387. However, that solution is not applicable to protective cushions for rail vehicles, which cushions are very large in volume, thereby requiring very high inflating pressures in order to obtain rapid deployment, thus causing the membranes closing the release orifices to rupture during inflation. In addition, reinforcing the membranes to prevent them from rupturing prematurely during inflation would lead to a reduction in the capacity of the inflatable cushion to absorb energy, in particular during small impacts, while increasing the pressure threshold above which the gas can escape from the cushion. Unfortunately, in order to obtain effective protection, it is important for the inflatable cushion to be properly inflated before impact and for it to relax as soon as impact occurs in order to prevent the inflatable cushion from deforming almost exclusively elastically during impact, e.g. with a human being, since it would then reaccelerate said human in the opposite direction after an impact and with a force of corresponding magnitude.
The object of the present invention is thus to propose a release device, and a protection device provided with such a release device, to ensure that the protection element is inflated without loss of gas so as to optimize deployment of the inflatable element, and also to ensure that the gas is released progressively as soon as impact occurs, however violent the impact.
To this end, the invention provides a release device for releasing an inflatable element for protecting a vehicle against impact, which element, once inflated, presents a general shape that fits closely over the region of the vehicle to be protected, the inflatable element being held, in a folded state, in a compartment and including an opening having an edge that is connected in sealed manner to a wall of the compartment, wherein, facing the opening, the wall includes gas release means that are protected during inflation of the inflatable element by a closure flap controlled by actuator means that remove the closure flap once the inflatable element is deployed.
In particular embodiments, the release device can comprise one or more of the following characteristics, taken in isolation, or in any technically feasible combination:
the closure flap is actuated by pyrotechnical or electrical control means;
the release means are constituted by one or more membrane-fitted release orifices, said membrane(s) being designed to tear when excess pressure is created by an object impacting on the inflatable element; and
the flap is removed after a time delay has elapsed from the initial triggering of the inflatable means.
The invention also provides a protection device for protecting a vehicle against impact, the protection device including an inflatable element which, once inflated, presents a general shape that fits closely over the region of the vehicle to be protected, the inflatable element being held in a folded state in a compartment that includes a wall that is connected in sealed manner to an opening of said inflatable element, wherein, facing the opening, the wall includes an orifice opening out to inflating means, and includes gas release means that are protected during inflation of the inflatable element by a closure flap controlled by actuator means that remove the closure flap once the inflatable element is deployed.
In particular embodiments, the release device can comprise one or more of the following characteristics, taken in isolation, or in any technically feasible combination:
the vehicle is a rail vehicle; and
the inflation means are constituted by a tank of gas under very high pressure.